1. Field of the Invention
The present invention relates to toner, especially a toner for developing an electrostatic latent image.
2. Description of Related Art
Lately, there is a rising demand for a more energy conserving image forming apparatus which performs image forming by electro-photography and toner which can be fixed at a low temperature is being developed.
In order to realize fixing at a low temperature, the binder resin and release agent in the toner need to be melted at a low fixing temperature. Therefore, typically, as binder resin and release agent in the toner, those with low melt viscosity are generally used.
In order to adapt to a much lower fixing temperature, a toner is disclosed in which the release agent has a lower melting temperature (for example, see Japanese Patent Application Laid-Open Publication No. 2002-162778, Japanese Patent Application Laid-Open Publication No. 2006-133749). However, further lowering of the fixing temperature results in the toner melting easily, and there is a problem that when sheets of paper on which fixing processing of the toner images are performed by double face printing are piled, a toner image on one sheet of paper soils a toner image of a contacting sheet of paper, and document offset occurs. Therefore, a toner where document offset does not occur is developed (for example, see Japanese Patent Application Laid-Open Publication No. 2007-114648).
Further, in a toner which can be fixed at a low temperature, the gloss of the toner image tends to be better, however gloss unevenness also increases. Therefore, there is a toner developed to even gloss and also to enable fixing at a low temperature (for example, see Japanese Patent Application Laid-Open Publication No. 2008-191652).
However, the ability to prevent document offset and to even gloss is still not enough.